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Interpretive data for breath tetrachloroethene

WEL: 20 ppm (8h TWA) - reduced in 2018

Other names: tetrachloroethylene, perchloroethylene


This information sheet provides interpretation of breath solvent values obtained using the Bio-VOC™ breath sampler. Further information regarding the implementation of a biological monitoring strategy can be found in HSE's 'Biological monitoring in the workplace' booklet.


Samples should be taken pre-shift, next day towards the end of the working week in a 'clean' area, such as medical room, office or canteen. Refer to the Breath Sampling Guidance Sheet for details of how to take samples.

Tetrachloroethene is poorly metabolised and stored in adipose tissue and so even a single exposure can be detected for several days after exposure. It is therefore likely that tetrachloroethene will accumulate in the body during a working week.


A well-conducted field study of 32 workers over a working week (1) showed that exposure to 50 ppm (TWA) of tetrachloroethene would give rise to 7 ppm (290 nmol/l) of tetrachloroethene in alveolar air when sampled 60 hours post exposure. A physiologically based pharmacokinetic model (2) confirmed this. The American biological exposure index (3) is 3 ppm (125 nmol/l) for an 8h TWA of 25 ppm .  SCOEL recommend the guidance value for an exposure of 20 ppm (8h TWA).

HSL Bio-VOC™ sampler has been used in surveys of workers in the dry cleaning industry and in determining environmental exposure to tetrachloroethene .


  • If breath tetrachloroethene levels are below 40 nmol/l, exposure is likely to be below the WEL. A suggested biological monitoring is once yearly, providing no change in working practices.
  • If breath tetrachloroethene levels exceed 40 nmol/l, exposure may approach the WEL. Regular monitoring (perhaps six monthly) is recommended to ensure that exposure remains under control.
  • If breath tetrachloroethene levels exceed 125 nmol/l, it is likely that tetrachloroethene exposure exceeds the WEL over an 8 hour time weighted average. A routine monitoring strategy is recommended, as is investigation of the efficacy of control measures. Very high exposures of tetrachloroethene  can occur in the dry cleaning industry during loading and unloading of the machines.

Other Biological Monitoring

Other means of biological monitoring include tetrachloroethene  in blood (for which there is also an American and a SCOEL guidance value).

Exposure Control

Tetrachloroethene  can be absorbed by inhalation or skin absorption.


  1. Monster A et al. (1983) Scand.J.Work.Environ.Health. 9 273-281.
  2. Leung H.W. (1983) Am.Ind.Hyg.Assoc.J. 53 (6) 369-374
  3. Biological Exposure Indices 2016. American Conference of Governmental Industrial Hygienists.
  4. SCOEL/SUM/133 (2009). Recommendation of the Scientific Committee on Occupational Exposure Limits for Tetrachloroethylene (Perchloroethylene).

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